226 GENERAL EVOLUTION. 



sive ; or, to use expressions more free from objection, by addition 

 of parts, and by subtraction of parts. It is further evident that 

 that animal which adds something to its structure which its par- 

 ents did not possess, has grown more than they ; while that 

 which does not attain to all the characteristics of its ancestors has 

 grown less than they. To express the change in the growth-his- 

 tory which constitutes the beginning of evolution, I have employed 

 the terms *^ acceleration and retardation." Generally these ex- 

 pressions are literally exact, i. e., there is an increased rate of 

 growth in evolution by addition, and a decreased rate in evolution 

 by subtraction ; but this is not always the case, for some divisions 

 of animals have increased the length of their growth-period with- 

 out reference to evolution in structure. The terms express the 

 phenomena figuratively, where not exact in the sense of time, and 

 I believe they are sufficiently clear. The origin of the fittest is 

 then a result of either acceleration or retardation. It is easy to 

 perceive that a character which makes its appearance in a j^arent 

 before or near to the breedino^ season is likelv to be transmitted to 

 its descendants ; so also a character which is lost near this time is 

 likely to be wanting from the offspring. The causes of accelera- 

 tion and retardation may next claim attention. 



It is well known that the decomposition of the nutritive fluids 

 within living animals gives rise, in the appropriate tissues, to 

 exhibitions of different kinds of forces. These are, motion in all 

 classes ; heat in some only ; in a still smaller number, electricity 

 and light ; in all. at certain times, growth-force or bathmism ; in 

 many, phrenism or mental or thought-force. These are all derived 

 from equivalent amounts of chemical force which are liberated by 

 the dissolution of protoplasm. This organic substance, consisting 

 of CHON, undergoes retrograde metamorphosis, being resolyed 

 into the simpler CDs, HO, etc., and necessarily liberates force in 

 the process. None of the functions of animal life can be main- 

 tained without supplies of protoplasm. TVe have here to do with 

 bathmism. It consists of the movement of material to, and its 

 deposition in, certain definite portions of the growing egg, or 

 foetus, as the case may be. It is different in its movements in 

 every species, and its direction is probably the resultant of a num- 

 ber of opposing strains. In the simplest animals its polar equili- 

 brium is little disturbed, for these creatures consist of nearly 

 globular masses of cells. As we ascend the scale a greater and 

 more marked interference becomes apparent ; radiated animals 



